Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455, USA
Address for correspondence: Timothy J. Ebner, M.D., Ph.D., Department of Neuroscience, University of Minnesota, Lions Research Building, 2001 Sixth St. S.E., Room 421, Minneapolis, MN 55455. Voice: 612-626-9200; fax: 612-626-9201.
ebner001{at}tc.umn.edu
Ann. N.Y. Acad. Sci. 978: 205-218 (2002).
Deciphering the information or signals carried by the complex
spike discharge of Purkinje cells has proven to be problematic,
primarily because of low frequency discharge and lack of adequate
analytical techniques. This problem is particularly acute for
studies of limb movements. To this end the relationship of cerebellar
Purkinje cell complex spike discharge to direction and speed
were studied in a manual-tracking task. Two monkeys were trained
to pursue track targets moving in one of eight directions and
at one of four speeds. An analysis based on Poisson regression
modeling fitted the complex spike counts during single movement
trials to target direction and/or speed. Using single trial
data, the Poisson modeling demonstrated that the complex spike
discharge for a majority of the Purkinje cells was significantly
fit to tracking direction and speed. A second analysis based
on the directional distribution of position and speed errors
and a Poisson regression model of complex spike discharge to
tracking position and speed errors found little relationship
to movement error. Comparison of the preferred direction of
the complex spike discharge with that of the simple spike activity
revealed a reciprocal relationship for many cells. Thus, the
complex spike discharge signals both tracking direction and
speed but not movement errors. Furthermore, treating complex
spike counts as a Poisson process provides a powerful tool for
analyzing these events in single trials, without the need for
extensive averaging.
